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1H-NMR spectroscopic studies of paramagnetic superstructured iron(III) porphyrinsThis article is dedicated to the memory of Professor Michel Momenteau of Institut Curie.Abbreviations. 1D and 2D: one-dimensional and two-dimensional; COSY: correlated spectroscopy; NOESY: nuclear Overhauser effect spectroscopy; TPP: 5,10,15,20-tetraphenylporphyrinate dianion.

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The electronic properties of several superstructured iron(III) porphyrins, in which the two faces of the porphyrin are protected by two chains linked at the opposite phenyl rings, have been investigated. The paramagnetic 1H NMR spectra of three iron(III) “basket-handle” porphyrins such as FeIII[e-BHP(C12)2], FeIII[a-BHP(C12)2] and FeIII[e-BHP(C12)(ImC11)] in organic solvent have been assigned. The 1H T1 values of the signals were measured and resonance assignments made based on NOESY and COSY experiments. The electronic structure of the iron(III) is discussed on the basis of the temperature dependence of the isotropic shifts and relaxation times. The hyperfine-shifted resonances in these spectra are compared with those of unhindered iron(III) porphyrins.